High temperature compression heater



Feb. 6, 1962 M. o. LAWSON HIGH TEMPERATURE COMPRESSION HEATER Filed Oct. 3, 1960 HOT GAS HIGH PRESSURE GAS SOURCE l COLD GAS HIGH PRESSURE GAS SOURCE INVENTOR. MAURICE LAWSON BY b ATTORNEY 3,l9,52.l latented Feb. 6, 1962 hoe 3,ll19,621 HEGH TEMPERATURE COR-EPIKESSIGN HEATER Maurice O. Lawson, 11.1 E. Schantz Ave, Dayton, @1110 Filed tint. 3, 1960, Ser. No. 60,233 8 llaims. (Cl. 62467) (Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to a device for producing high temperature gas.

One object of the invention is to provide a device for producing high temperature gas whichoan be used in hypersonic wind tunnels.

This and other objects will be more fully understood from the following detailed description taken with the drawing, wherein: I

FIGURE 1 is a gas heater according to one embodiment of the invention; and,

FIGURE 2 is a modification of the device of FIG- URE 1 according to another embodiment of the invention.

Referring more particularly to FIGURE 1 of the drawing, reference number refers to a tubular chamher having an insulation coating 11 on the inside surface. Pressurized gas from a high pressure gas source 12 is admitted to chamber 10 by means of a fast opening cyclical inlet valve 13. A cyclical outlet valve 14 is operated approximately 180 out of phase with respect to the inlet valve 13 and is opened for a greater period of the cycle than the inlet valve. The periods should overlap slightly for best operation; however, this is not absolutely necessary as the device will operate without this overlap. The hot gases which have been heated in chamber 10 are permitted to flow out of the outlet 15 by means of a throttle valve 16. The gases passing through the cyclical outlet valve 14 pass to the cold gas outlet 17 through a throttle valve 18. The valves 16 and 13 may be made variable if desired.

The device of FIGURE 2 is similar to the device of FIGURE 1 and has a throttling orifice 20 provided to further heat the gases which are displaced back and forth through said throttling orifice during each compression expansion cycle. It is obvious that several such throttling orifices could be provided if desired. A high temperature insulation chamber 21 is provided between the high temperature outlet and the throttle 25 so that the portion of the charge gas entering the region beyond the throttle 26 will pass back through the throttle ahead of the hot gases in chamber 21. This chamber also acts to maintain a substantially constant pressure at the output and therefore is also a pressure equalization chamber. In case of excessive heat in the area of orifice 20, a cooling jacket such as 22 may be required.

In the operation of the device in FIGURE 1, when valve 13 is opened a charge of gas from source 12 en ters chamber 1% so that a strong non-isentropic adiabatic compression occurs due to a shock traveling down the tube and reflected at the end of the tube and then further reflected at the interface of the compressing gas and the charge gas. When this happens, a portion of the charge gas which fills only a small fraction of the cylinders length between points a and b at the end of one compression expansion cycle is displaced to the section between points b and c and its temperature has been increased since it has undergone a non-isentropic adiabatic compression expansion cycle and is returned to its original pressure. At the end of another cycle this same gas has been displaced to the section c--d and its temperature further raised. Each cycle raises the temperature and displaces the gas towards the hot discharge exit while during each cycle additional charge gas enters chamber 10. The temperature of the gas leaving the output 15 is dependent upon the initial temperature of the gas, the length ratio of the cylinder to the added charge length a-b, the non-isentropic nature of the compression expansion cycle and adverse efiects, such as heat losses to the cylinder wall and to the driver gas. Insulation is provided to minimize the heat con duction losses through the cylinder wall. During the compression portion of the cycle, a charge of hot gas is driven out through the throttle valve 16 to the output 15. When valve 14 opens and after valve 13 is closed,

gas in chamber 10 is allowed to expand driving all of the gas admitted through valve 13 out through throttle valve 18 except a small amount needed to replace the hot gas driven out through valve 16. The size of the throttle valve ports 16 and 18 are chosen so that about 30 parts of cold gas pass through valve 18 for every one part of gas discharged through valve 16.

With one device built, valves 13 and 14 were rotary type valves which were operated at approximately cycles per second. The length of the cylinder 10 was made approximately 18 inches. The valve 16 and 18 were set so that for one part of gas at outlet 15 there were thirty parts of cold gas at outlet 17. In this device a temperature increase of about 1.8 to 1 from input to output was produced. The temperature of the gas from source 12 was 500 R. and the pressure was p.s.i.a. so that the gas at the outlet 15 was 900 R. The gas at cold gas outlet 17 was found to have dropped 50 R. in temperature.

The values given above are meant to be merely illustrative and not limiting since the size of the unit and operating conditions are determined by the particular use for which the device is intended.

There is thus provided a device for producing hot gases which may be used in hypersonic wind tunnels or other devices wherein the need for the use of hot gases exists.

While certain specific embodiments have been described in detail, it is obvious that numerous changes may be made without departing from the general principles and scope of the invention.

I claim:

1. A device for producing high temperature gas com prising: a tubular chamber, a layer of insulation on the inner wall of said chamber, a high pressure gas source, means for cyclically admitting gas from said high pressure source to said chamber, a second means for allowing gas to leave said chamber under expansion, said second means being operated out of phase with respect to said first means, a first outlet means for discharging hot gas from said chamber, and a second outlet, adjacent said second means, for discharging cold gas from said chamber.

2. A device for producing high temperature gas comprising: a tubular chamber, a layer of insulation on the inner wall of said chamber, a high pressure gas source, a first cyclically operating means for admitting gas from said high pressure source to said chamber, a second cyclically operating means for allowing gas to leave said chamber under expansion, said second means being operated out of phase with respect to said first means, a first outlet at the opposite end of said chamber from said first cyclically operating means for discharging hot gas from said chamber, and a second outlet adjacent said second cyclically operating means for discharging cold gas from said chamber.

3. A device for producing high temperature gas comprising: a tubular chamber, a layer of insulation on the inner wall of said chamber, a first outlet means for discharging hot gases from said chamber, a second outlet means for discharging cold gases from said chamber, a high pressure gas source, a cyclically operating inlet valve between said gas source and said chamber, and a second cyclically operating valve between said chamber and said cold gas outlet, said second valve being operated out of phase with respect to said first valve.

4. A device for producing high temperature gas comprising: a tubular chamber, a layer of insulation on the inner wall of said chamber, a throttling orifice within said chamber, a high pressure gas source, means for cyclically admitting gas from said high pressure source to said chamber, a second means for allowing gas to leave said chamber under expansion, said second means being operated out of phase with respect to said first means, a first outlet means for discharging hot gas from said chamber, and a second outlet, adjacent said second means, for discharging cold gas from said chamher.

5. A device for producing high temperature gas comprising: a cylindrical chamber, a layer of insulation on the inner wall of said cylinder, a throttling orifice within said chamber, a high pressure gas source, means for cyclically admitting gas from said high pressure source to said cylindrical chamber, a second means for allowing gas to leave said chamber under expansion, said second means being operated out of phase with respect to said first means, a first outlet means for discharging hot gas from said cylindrical chamber, and a second outlet, adjacent said second means, for discharging cold gas from said cylindrical chamber.

6. A device for producing high temperature gas comprising: a tubular chamber, a throttling orifice within said chamber, a layer of insulation on the inner wall of said chamber, a first outlet means for discharging hot gases from said chamber, a high temperature insulation,

pressure equalization chamber between said tubular chamber and said first outlet, a second outlet means for discharging cold gases from said chamber, a high pressure gas source, a cyclically operating inlet valve between said gas source and said chamber, and a second cyclically operating valve between said chamber and said cold gas outlet, said second valve being operated out of phase with respect to said first valve.

7. A device for producing high temperature gas comprising: a cylindrical chamber, a throttling orifice within said chamber, a layer of insulation on the inner wall of said chamber, a first outlet means for discharging hot gases from said chamber, a high temperature insulation, pressure equalization chamber between said cylindrical chamber and said first outlet, a second outlet means for discharging cold gases from said chamber, a high pressure gas source, a cyclically operating inlet valve between said gas source and said chamber, and a second cyclically operating valve between said chamber and said cold gas outlet, said second valve being operated out of phase with respect to'said first valve.

8. A device for producing high temperature gas comprising: a tubular chamber, a high pressure gas source, means for cyclically admitting gas from said high pressure source to said chamber, a second means for allowing cold gas to leave said chamber under expansion, said second means being operated out of phase with respect to said first means, means for extracting heat from said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,711,097 Kratzer Apr. 30, 1929 1,952,281 Ranque Mar. 27, 1934 2,560,728 Lee July 17, 1951 

